Motor-controlling device.



L. L. TATUM.

MOTOR CONTROLLING DEVICE.

APPLICATION FILED FEBJI, 1910.

1,007,402, Patented Oct. 31, 1911.

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LEWIS L. TATUM, 0F MILWAUKEE, WISCONSIN.

MOTOR-CONTROLLING DEVICE.

Specification of Letters Patent.

Patented Oct. 31, 1911.

Application filed February 11, 1910. Serial No. 543,296.

To all whom it may concern;

Be it known that I, LEwis L. TATUM, a citizen of the United States, residing at Milwaukee, in the county of Milwaukee and State of IVisconsin, have invented new and useful Improvements in Motor-Controlling Devices, of which the following is, a full, clear, concise, and exact d scription, reference being had to the-accompanying drawing, forming a part of this specification.

My invention relates to improvements in motor controlling devices and more particularly to motor starting rheostats.

One object of my invention is to provide a rheostat which, upon the occurrence of abnormal conditions, will disconnect the motor from circuit, regardless of the position occupied by its controlling element.

A further object of my invention is to provide a device of this character especially adapted for rear of switch board use.

Various other objects and advantages of my invention will be hereinafter set forth.

For the purpose of more clearly disclosing the nature and characteristic features of my invention, I shall describe the embodiment thereof illustrated in the accompanying drawing. It should be understood, however, that my invention is not limited to the particular form of device illustrated, but is susceptible of Various modifications.

In the accompanying drawing, Figure 1 is an elevation of the device; Fig. 2 is a side elevation thereof with the supporting panel shown in section; and Fig. 3 is a schematic view of the device showing diagrammatically one arrangement of circuit connections therefor.

The device is preferably provided with an insulating front or panel 1 of slate or other suitable material, and a casing 2 secured to said front for inclosing the resistance units (not illustrated). Secured to the lower portion of the panel 1 by means of screws 4 is a bearing plate 5 having a bearing portion 6. The plate 5 is preferably so arranged that the bearing portion 6 will be disposed below the lower edge of the panel.

. 1. The purpose of this arrangement will be hereinafter explained. Revolubly mounted in the bearing portion 6 of the plate 5 is a spindle or shaft 7 The shaft 7 is arranged to extend through the supporting panel 3 and has secured to the outer end thereof a suitable operating member 8, preferably in the form of a hand wheel. In practice, I

prefer to form the shaft 7 in two parts and to connect the same by means of a suitable insulating coupling 7 of any preferred type. Revolubly mounted on the rear end of the shaft 7 is an arm 9 carrying at its upper end and suitably insulated therefrom a contact member 10 adapted, upon movement of said arm to sweep over a series of contact buttons 11. The arm 9 is preferably cast or formed with a hollow rectangular portion 12 in which is mounted a suitable electromagnet 13, the purpose of which will be hereinafter set forth.

In practice, I prefer to bias the arm 9 to its extreme right hand position as illustrated in Fig. 1, and, for this purpose, I have provided a coil spring 14 surrounding the shaft 7. For operating the arm 9, I have provided an arm 15 fixed or keyed to the shaft 7. This arm is adapted to be locked to the arm 9, and is, consequently, subject to the bias of said latter arm. I, therefore,

preferably provide an electromagnet 17 for holding said arms in their extreme left hand position, said arm 15 having an armature 16 adapted to be attracted and held by said magnet.

For the purpose hereinafter explained, I prefer to provide a releasable connection between the two arms which, in practice, may assume various forms. The connection illustrated comprises a latch 18 pivoted to the arm 15 and having a notched portion therein for engaging a pin or stud 20 on the arm 9. Downward movement of the latch 18 is limited by stop 19, and the free end of said latch is so arranged that if the arms become separated the latch 18 will automatically engage the pin 20 upon movement of the arm 15 toward the arm 9. The purpose of the magnet 13 is to cause the release of the arm 9 from the arm 15 upon the occurrence of certain electrical conditions. For causing the magnet 13 to accomplish this result, I provide the same with a movable plunger 21, having an extension 22 adapted to engage and raise the latch 18 when said magnet responds. This, of course, releases the arm 9 which is then moved by the spring 14 to its initial position.

In Fig. 3 I have shown this device arranged to control an electric motor having an armature A and a shunt field winding F. Of course, in practice, the device may be used to control various types of motors. The device is arranged to control a resistarm 15.

ance 28 connected to the contact buttons 11 and arranged in circuit with the motor armature. The magnet 13 is also connected in circuit with the motor armature, and, therefore, SL1l)]Ct to varlations 1n the flow of current therethrough. Thls wmdlng has one terminal connected to the main portion of the contact arm 9 and its other terminal connected to the contact member 10 of said The magnet 17 may be connected in circult in various dlfferent ways, but is preferably connected in circuit with the shunt field winding F.

I shall now describe the operation of the device, at the same time more clearly setting forth the c1rcu1t connections.

25 and 26, and that the arms of the :device are in the position illustrated, no current; will flow through the motor. As illustrated, f the arm 9 is released from the operating. Consequently, in order to close the motor circuit, it is necessary to zfirst move the hand wheel 8 in a direction :to; move the arm 15 toward the arm 9. When the arm 15 is moved in this direction, the

9, thereby locking the arms together. The

hand wheel may then be turned in the opposite dlrection, drawing the arm 9 into en-Y gagement with the contact buttons 11. This immediately results in closing a circuit from main line 25 to the bearing plate, thence through the lower portion of the arm 9 and magnet 13 to contact member 10, thence through the first of the contact buttons 11 and resistance 28, through the motor armature to main line 26. At the same time circuit is closed from the first of the con tact buttons, through the magnet 17 and field winding F in series to main line 26. Thus upon initial movement of the arm 9 circuit is closed through the motor with all of the resistance 28 included in circuit with the motor armature. Continued movement of the arm 9 gradually removes the resistance '28, thereby accelerating the motor.

l/Vhen the arm 9 has been :moved suflicientlyto short-circuit all of the resistance 28, the

armature 16 carried by the arm 15 will engage the poles of the magnet 17 and said magnet will thereupon retain :both arms in full running position. If, however, there is a failure of voltage at any time, the magnet 17 will become deenergized, thereby re leasing the arms, which will return to initial position under the influence of the spring 14.

The magnet 13 may be adjusted to respond'whenever the flow of current through the motor armature exceeds a safe limit. When so adjusted, it will respond upon ex- Assuming that current 1s supplled from mam lines cessive surge of current through the motor armature to disengage the latch 18 from the pin 20, thereby freeing the arm 9. The arm 9 immediately returns to initial position under the influence of the spring 14, thereby opening the motor circuit. With this arrangement, the release of the arm 9, upon the occurrence of an overload, is insured even while it is being moved to accelerate the motor. Hence, whether the overload occurs through too rapid removal of the resistance 28 or from any other reason, the motor is fully protected. After the occurrence of an overload and the release of the arm 9, it is necessary to return the arm 15 to initial position to cause it to lock with the arm 9 before the motor can be again started.

The purpose of extending the bearing ,plate 5 below the panel 1 is two-fold. First, this arrangement obviates the necessity of extending the shaft 7 through the resistance containing portion of the device with the obvious advantage that the danger of short-circuits is eliminated. Second, this arrangement permits a given linear movement of the contact arm 9 over the contact but- ;tons with a small angular movement thereof. This renders it practical to mount the overload coil on the arm 9 as the small angular movement will have little or no effect upon the calibration of said magnet.

Having thus described my invention, what I desire to secure by Letters Patent is:

1. In combination, a resistance controlling element, an operating element therefor, a releasable connection between said elements and an electromagnet carried by one of said elements for releasing said resistance controlling element from said operating element, said connection being effective independently of said electromagnet.

2. In combination, a pivoted resistance controlling element, a pivoted operating element therefor, a releasable connection be tween .said elements and an electromagnet carried by one of said elements for causing the release of said controlling element from said operating element under predetermined conditions, said connection being effective independently of said electromagnet.

In' combination, a pivoted resistance controlling element, a pivoted operating element therefor, releasable connections between said elements and an electromagnet carried by one of said elements and having a :movable plunger for causing the release of said controlling element from said operating element under predetermined conditions, the element carrying said electromagnet being arranged to move between certain limits with a small angular movement thereof.

4. In combination, a pivoted resistance controlling element, an operating element therefor, releasable means for securing said elements together, and an electromagnet carried by said resistance controlling element and having a movable plunger for operating said means to release said resistance controlling element from said operating element under predetermined conditions, said resistance controlling element being arranged to move from one extreme position to the other with a small angular movement thereof.

5. In combination, a resistance controlling element biased to move in one direction, an operating element therefor, a latch for connecting said elements to move in unison, and an electromagnet carried by one of said elements for actuating said latch to release said controlling element from said operating element.

6. In combination, a resistance controlling element biased to move in one direction, an operating element therefor, a latch for connecting said elements to move in unison, and

an electromagnet carried by one of said elements for actuating said latch to release said controlling element from said operating element, said latch being adapted to automatically lock said elements together when said operating element is moved toward said resistance controlling element.

7. In combination, a resistance controlling element, an operating element therefor, releasable means for securing said elements together, and an electromagnet carried by one of said elements for actuating said means to release said resistance controlling element from said operating element under predetermined conditions, the element carrying said magnet having portions forming a frame around said magnet.

8. In combination, a pivoted resistance controlling element, an operating member therefor, means for connecting said member to said element, an overload magnet carried by said element for releasing the same from said operating member under predetermined conditions, said element having portions forming a frame around said magnet, a contact member carried by said element and insulated therefrom, said magnet having one of its terminals connected to said element and its other terminal connected to said contact member.

9. In combination, a resistance controlling element biased toward off position, an operating member therefor, means for connecting said member to move in unison, an overload magnet carried by one of said elements for operating said means under predetermined conditions to release said controlling element from said operating element, and a retaining magnet for holding said element in full on position.

10. In a motor starting device, in combi nation, a pivoted resistance controlling element biased toward off position, a pivoted operating element therefor, means for connecting said operating element to said controlling element, an overload magnet carried by one of said elements for releasing-said controlling element from said operating element upon the occurrence of abnormal conditions in the motor circuit, and a low voltage magnet for holding said operating element in final position.

11. In combination, a supporting panel, a rheostat secured to the rear side thereof, said rheostat having an insulating panel thereon, a series of contacts on the outside of said panel, a bearing plate secured to said panel and projecting below the lower edge thereof, a revoluble shaft passing through said bearing plate and said supporting panel, and a contact member mounted on said shaft and movable over said contacts.

12. In combination, a current carrying member, an operating member therefor, and electromagnetically controlled means for releasably connecting said members to move together, including an electromagnet mounted on said current carrying member, and having its winding terminals connected thereto.

In witness whereof, I have hereunto subscribed my name in the presence of two witnesses.

LEWIS L. TATUM.

Witnesses:

FRANK H. HUBBARD, E. W. WUSSON.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. C. 

